Parametric study on hematite pellet direct reduction by hydrogen

This study investigates the intrinsic kinetics of hematite reduction to iron using hydrogen through the utilization of a computational fluid dynamics (CFD) coupled with a modified unreacted shrinking core model. The new mathematical model is developed to analyze the reduction process of a real pellet, taking into account the variation in porosity at different reaction rates. The impact of temperature, particle size, gas inlet velocity, and porosity on hydrogen-based direct reduction were investigated. The study reveals that size affects reduction degree at temperatures below 973 K, while it is independent of size at 1273 K. The optimal inlet velocity is 0.28 m∙s⁻¹, and the time for complete reduction is over 3500 s and 800 s at 973 K and 1273 K, respectively. The numerical results align with experimental results. The study provides a solid foundation for dynamic modeling of reduction process but further work is needed for a realistic model.